1366 - Incorrect integer value: '' for column 'customer_id' at row 1

insert into whos_online (customer_id, full_name, session_id, ip_address, time_entry, time_last_click, last_page_url) values ('', 'Guest', 't24imp9acb4pgf3vr687k7d7r7', '216.73.216.87', '1769280431', '1769280431', '/shop_content.php?XTCsid=3f98699a7205aa16d7f8014dc7c0d34a&coID=4')

[XT SQL Error]